<html>
    <head>
        <meta charset="utf-8">
        <title>标题</title>
    </head>
    <head>
        <script>
            function start1(){
                setTimeout(
                    function(){
                      alert("没想到这么快吧")
                      confirm("可以点取消的")
                      prompt("傻了吧，有什么想说的：")
                      confirm("没想到吧，说了也没用")
                      confirm("嘿嘿嘿")
                      confirm("溜了溜了")
                    },100
                );
            }
            function start2(){
                var i = 85;
                var s = setInterval(
                    function(){
                        document.write(i + "");
                        i -- ;
                        if(i == 0){
                            clearInterval(s);
                        }
                    },50
                );
            }
        </script>
    </head>
    
    <body>
        <a href="#" onclick="start1()"> 定时</a>
        <a href="#" onclick="start2()"> 倒计时</a>
    </body>
</html>